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Where's the Beefsteak?
Searing Summer Heat Stresses Tomato Plants

By Adrian Higgins
Washington Post Staff Writer
Thursday, August 31, 2006; H01

Is it getting tougher to raise a decent tomato?

Many backyard tomato growers are reporting a particularly poor showing this year, with scrawny, diseased vines and pathetic harvests.

Megan Gardner, a Virginia Cooperative Extension horticulturist and tomato troubleshooter, has heard two telling comments in her travels in Virginia's Middle Peninsula: Folks complain "that nobody has offered them extra tomatoes this year," she said. "When those who have extra tomatoes gave them away, everyone took them."

Tomatoes fail for a host of reasons, some in the gardener's control, others not. One theory is that high heat and related tomato stress this summer are another product of global warming.

Whatever the cause, gardeners are looking afresh -- and askance -- at what was believed to be not only an easy summer vegetable but a birthright for city patio farmers and suburban ranchers alike.

"People hold them close to their hearts," said Gardner, "but I think they're fairly difficult for a home gardener" to grow successfully.

Chuck Ropp of Arlington was among a dozen growers contacted to assess the crop. He said this in an e-mail: "I grew up on a farm and have always gardened. This is by far the worst year I have ever had." Two seedlings died after planting in late April, two more lacked vigor and were pulled, and six others have limped along. He also grew two beefsteak varieties that have suffered from blossom end rot, a disease linked to uneven watering and calcium deficiency, even though he has been seeing to them. "The heirloom varieties that I planted did not get the rot, but several did not flower," he wrote.

In the Del Ray neighborhood of Alexandria, Germaine Schaefer put in 14 plants, including four cherry varieties and assorted heirlooms and hybrids. "Cosmonaut Volkov was the first to die, then the Mountain Princess got the yellow wilt," she said, referring to a foliar disease called early blight. Another common ailment is Septoria leaf spot. A Green Zebra and beefsteak have languished, and plants from the local farmers market, which produced well at first, are moribund.

"The Brandywines were a bust," she said. "We had four: one we have eaten and three the squirrels have eaten." She shares the garden with a neighbor. "With 14 plants I was hoping to be inundated with tomatoes," she said. "Instead, it's just been a decent harvest, giving both our families [a total of six people] enough for daily meals, but not enough to share with others."

Some backyard gardeners report a fairly normal harvest, though with plants that fruited early or with cherry tomatoes, which are typically more robust and fruitful than larger types. Enriched soil, soaker hoses and, in some cases, plastic mulch, helped to keep more moisture in the soil than in tomato patches without those elements.

"The cherry varieties were prolific, but I've also had many fruits from the white peach, a Black Russian [variety], the Marmande, and some others," said Jaye Falls, of Annapolis.

But there are far more losers than winners this season, judging by readers who e-mailed and my own observations of gardens -- including, alas, my own. In Wheaton, Craig Kent can tally his harvest of keepers on one hand, with a finger and thumb to spare. "The worst year that I can recall," he said by e-mail.

In Arlington, Liz and Ken Walsh planted two beefsteak varieties, a smaller hybrid and four cherry tomato plants. They allowed a couple of volunteer seedlings to grow. They picked "pints and pints" of cherry tomatoes, but only five of the full-size fruit.

They had 10 more going, but those were eaten by an animal that Liz Walsh thinks was a vole. As August became unbearably hot and dry, she concedes, she didn't stay on top of the weeds.

"The weather was so variable, and it had a negative effect," said Jon Traunfeld, a fruit and vegetable specialist at the Maryland Home and Garden Information Center. "Everything was slow getting started, then we got a lot of rain, and then it pretty well turned dry in July and August. Unless somebody had pretty decent soil and really took care of their plants, it was below par."

There are ways to minimize problems with tomatoes. Use deep, rich soil with sufficient calcium and organic matter. Apply mulch to keep down weeds and blight spores. Make sure you have sufficient staking to keep vines upright and sufficient spacing to minimize fungal diseases. Also helpful: perhaps a little afternoon shade to reduce the risks of sun scald on the fruit.

Chances of success also are increased with soaker hoses or drip irrigation that moisten the soil but keep water off the leaves, as well as the diligence of the gardener to keep abreast of pests and diseases. Even with mulch, says Traunfeld, blight is such a problem that spraying is needed to keep plants clean and healthy, and copper sprays are organic and effective.

But there are some things the gardener cannot control. Tomatoes like it hot, but not the heat of Washington in August. The problem is not just the high daytime temperatures, but the night temperatures, which stress the plant and conspire to kill the blossoms before they can fruit. In the early August heat wave, for example, the lowest the thermometer reached was about 80 degrees.

Flower viability suffers when the daily mean temperature climbs above 77 degrees, said Mary Peet, a professor of horticulture at North Carolina State University. After five to seven days of such unrelenting heat, "not as much pollen is produced, it's less vigorous and less likely to be released by the anthers."

"My sense is, because of global warming, that in 10 of the last 11 years our nighttime temperatures in urban areas have increased," said Traunfeld, "so bloom set is going to be affected."

Peet points out that in warmer North Carolina, tomatoes tend to be grown to fruit in July rather than August, and wonders if that might become the model for Washington. This would mean setting plants out earlier and protecting them on cooler spring nights.

Traunfeld points out that oversize tomatoes such as beefsteaks, oxhearts, Brandywine and other mammoth heirlooms tend to set fewer fruit and then take several weeks to grow and ripen, exposing them to greater risks of problems than smaller, earlier-fruiting varieties.

Liz Walsh, meanwhile, is among local tomato fans in need of encouragement. Part of her wants to forget them, but she realizes summer wouldn't be the same without them. "I hope to get some next year. Hopefully."

© 2006 The Washington Post Company